1. Field of the Invention
The present invention presents an electrostatic discharge (ESD) protection device for an output driver circuit, more particularly, an electrostatic discharge (ESD) protection for protection of an output buffer of an output driver circuit.
2. Description of the Prior Art
FIG. 1 illustrates a circuit of an electrostatic discharge (ESD) protection device 100 according to a prior art. The ESD protection device 100 is coupled to an internal circuit 101. The ESD protection device 100 has an output buffer T1 and an electrostatic discharge (ESD) cell T2 coupled to an output pad PAD1. When an electrostatic discharge (ESD) event occurs in the output pad PAD1, majority of current of the ESD event is driven to the ground through the ESD cell T2 and some of the current from the ESD event will go through the output buffer T1 since the output buffer T1 is partially turned on.
The amount of current going through the output buffer T1 and the ESD cell T2 is divided using percentage. For example, 80% of the current of the ESD event goes through the ESD cell T2 and 20% of the current of the ESD event goes through the output buffer T1. As the current of the ESD event gets higher, the current that goes through the output buffer T1 also gets higher. Therefore, the output buffer T1 is not completely protected by using the ESD cell T2.